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Re: [Xen-devel] [PATCH RFC 02/15] xen/arm: move a few guest related #defines to public/arch-arm.h


On 02/07/18 22:38, Stefano Stabellini wrote:
On Mon, 2 Jul 2018, Julien Grall wrote:

On 02/07/2018 21:37, Stefano Stabellini wrote:
On Fri, 15 Jun 2018, Julien Grall wrote:
Hi Stefano,

On 06/14/2018 10:15 PM, Stefano Stabellini wrote:
On Thu, 14 Jun 2018, Julien Grall wrote:
On 13/06/18 23:15, Stefano Stabellini wrote:
Move a few constants defined by libxl_arm.c to
xen/include/public/arch-arm.h, so that they are together with the
guest related #defines such as GUEST_GICD_BASE and GUEST_VPL011_SPI.
Also, this way they can be reused by hypervisor code.

All variables moved to arch-arm.h should be prefixed with GUEST_* to
clash with the rest of Xen.

I'll do.

Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
CC: wei.liu2@xxxxxxxxxx
CC: ian.jackson@xxxxxxxxxxxxx
     tools/libxl/libxl_arm.c       | 26 --------------------------
     xen/include/public/arch-arm.h | 26 ++++++++++++++++++++++++++
     2 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/tools/libxl/libxl_arm.c b/tools/libxl/libxl_arm.c
index 8af9f6f..89a417f 100644
--- a/tools/libxl/libxl_arm.c
+++ b/tools/libxl/libxl_arm.c
@@ -8,23 +8,6 @@
     #include <libfdt.h>
     #include <assert.h>
- * IRQ line type.
- * DT_IRQ_TYPE_NONE            - default, unspecified type
- * DT_IRQ_TYPE_EDGE_RISING     - rising edge triggered
- * DT_IRQ_TYPE_EDGE_FALLING    - falling edge triggered
- * DT_IRQ_TYPE_EDGE_BOTH       - rising and falling edge triggered
- * DT_IRQ_TYPE_LEVEL_HIGH      - high level triggered
- * DT_IRQ_TYPE_LEVEL_LOW       - low level triggered
- */
-#define DT_IRQ_TYPE_NONE           0x00000000
-#define DT_IRQ_TYPE_EDGE_RISING    0x00000001
-#define DT_IRQ_TYPE_EDGE_FALLING   0x00000002
-#define DT_IRQ_TYPE_EDGE_BOTH                           \
-#define DT_IRQ_TYPE_LEVEL_HIGH     0x00000004
-#define DT_IRQ_TYPE_LEVEL_LOW      0x00000008

Those defines have nothing to do with the guest itself. They are
define in Xen without the DT_ prefix.

Sounds like we want to get rid of the DT_IRQ_TYPE_* definitions
completely, move the IRQ_TYPE_* definitions from device_tree.h to here,
and start using them in tools/libxl/libxl_arm.c (which involves a
renaming s/DT_IRQ_TYPE/IRQ_TYPE/g).

Is that what you had in mind?

Even if DT is Arm only today, the DT code is in common code and therefore
header device_tree.h should contain every thing necessary to use a DT.

If we still want to share constant with libxl then I would prefer to
a new header (similar to acpi/acconfig.h) that provide all the common

OK, I can do that. I'll introduce a new header file.

Note that the hypervisor one don't have the DT_ prefix because they are
use to
describe IRQ for both DT and ACPI in Xen. It is not that nice, we might
to introduce aliases in that case. So we keep DT_* in libxl.

With the new header file we'll be able to reuse the same #defines in
libxl and xen. I think it would be nicer to avoid the aliases and just
use the regular definitions in libxl too? Changing libxl to use
IRQ_TYPE_ directly only requires a small patch.

I really don't want that. As I explained, IRQ_TYPE have been conveniently
chosen to avoid converting DT value to IRQ_TYPE. They are not meant to be use
like that libxl (or any header publicly shared) and will provide more
confusion that anything for other bits than the hypervisor.

I don't follow the explanation. Why would they be confusing in public
headers? What is the important difference between DT_IRQ_TYPE_* and
IRQ_TYPE_* that we are trying to keep? Why IRQ_TYPE_* shouldn't be used
by libxl?

Because IRQ_TYPE_* does not have the prefix DT_ in them. There are no way from the name to say this is for DT only and might be misused outside of the hypervisor.

IRQ_TYPE_* used to have the prefix DT_ but it was dropped as in the hypervisor they are used to represent irq type for both ACPI and DT. If we end up to expose those values to libxl then we should define DT_IRQ_TYPE_* and provide aliases for IRQ_TYPE_.


Julien Grall

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